The simple fact is sometimes a truly great game becomes massive, and sometimes its only a good game.
Halo was a good FPS that, because it was on a console, was judged a great FPS and groundbreaking. It was a key element of Xbox giving gamers (particularly in US) a PC like experience on a console, including MP.
From that beginning it became the massive seller it now is.
Yet as an SP FPS the quality actually went down I would argue, while the MP quality went up - but again this actually sat well with the masses.
So, can RFOM2 be a 'halo' for PS3 (i.e. become a larger selling game with its own identify?)... maybe. I think its much harder to do that now, though. If Halo released now it would just be another console FPS for example.
But it could, just... its got the base now from RFOM and is linked to PS3. RFOM2 looks like it could really be a big leap and the install base is hungry for it to succed... so it could, and I think the key is the MP and Co-op. If they really shine then it could sell bucket loads and become a true signature franchise.
Try to be reasonable... its easier than you think...
